1. Field of the Invention
The present invention relates to an image printing apparatus and, more particularly, to an image printing apparatus which has a tray for placing printing media thereon and prints an image, on the basis of a job, on a printing medium supplied from the tray.
2. Description of the Related Art
In an image printing apparatus having an interrupt function of interrupting execution of a predetermined job and executing another interrupt job and a job management function with which the execution priority levels of jobs stored in a storage section can be changed, when a post-determined job such as an interrupt job or priority level-changed job is executed first, the predetermined job must be complete without any error.
When a given user sets special paper sheets such as coated paper sheets or embossed paper sheets in a tray of an image printing apparatus, he wants to use these paper sheets only for himself. When the image printing apparatus is used by a plurality of users in a network environment, the special paper sheets set in the tray may be used by a post-determined job of another user. The given user wants not to allow another user to use the tray designated by the given user.
To solve the above problems, according to one proposal, in an image printing apparatus having an interrupt function of interrupting execution of a predetermined job and executing another interrupt job, when a tray selected by an interrupt job is the same as that selected by the predetermined job, printing of the interrupt job is inhibited, or the interrupt job is inhibited from selecting the tray selected by the predetermined job. For example, see Japanese Unexamined Patent Publication No. 2001-331064 (patent reference 1). Patent reference 1 also proposes that the tray selected in printing the predetermined job is physically locked and cannot be unloaded.
According to another proposal, when selecting a tray for a post-determined job, selection of a tray already selected by a predetermined job is inhibited. For example, see Japanese Unexamined Patent Publication No. 11-292329 (patent reference 2). The tray selected by the predetermined job will not be selected by the post-determined job. The predetermined job is always printed on the desired paper sheet.
Still another image printing apparatus is proposed in which when a predetermined job which uses a tray designated by a user but does not allow use of this tray by another job is complete, the selection inhibition can be automatically canceled. For example, see Japanese Unexamined Patent Publication No. 2004-106424 (patent reference 3). This makes it possible to prevent a decrease in use efficiency of the tray.
Still another image printing apparatus is proposed in which in job reservation, a sheet set in a manual feed tray is fed by a paper feed section to an apparatus main body. For example, see Japanese Unexamined Patent Publication No. 2003-228204 (patent reference 4). A sheet selected by a given user can be prevented from being changed by the next user. This makes it possible to reliably ensure the priority on sheet selection by the given user.
In patent references 1 to 3, however, the post-determined job which designates the tray coinciding with that of the predetermined job cannot be accepted until the end of the predetermined job. The user of the post-determined job, who wants to use the same tray as that of the predetermined job, must wait for setting a job for selecting the tray occupied for the predetermined job until the end of the predetermined job. This scheme is very poor in working efficiency for the user who sets the post-determined job. This also results in disadvantages from the viewpoint of mental hygiene. While the user who wants to set the post-determined job proceeds another job until the end of the predetermined job, he may forget to set the post-determined job, resulting in a large delay in delivery of printing products. The use efficiency of the tray occupied for the predetermined job often decreases greatly.
In patent reference 1, tray unloading is inhibited after the image printing operation of the predetermined job is complete. However, before the predetermined job is executed, another user may unload the tray and replace the paper sheets with desired paper sheets.
In patent reference 4, a holding device which temporarily holds sheets is required in addition to the tray. The apparatus becomes bulky in producing a large number of printing products.